preterm premature rupture of membranes

**Definition** - PROM: rupture of membranes before onset of labor, at any gestational age. - PPROM: PROM occurring at <37 0/7 weeks. It complicates ~2-3% of pregnancies and accounts for ~30-40% of preterm births. - Previable PPROM: before ~23-24 weeks. Prolonged PROM: latency >18-24 h before delivery, which raises the risk of infection.

**Risk factors** - Prior preterm birth or prior PPROM (strongest risk factor) - Genital tract infection or intraamniotic infection (GBS, Chlamydia, Gonorrhea, bacterial vaginosis, Trichomonas) - Short cervix, cervical insufficiency, or prior cervical surgery (conization) - Second- and third-trimester bleeding or abruption - Polyhydramnios and multiple gestation (uterine overdistension) - Smoking, low BMI, low socioeconomic status - Connective tissue disorders (Ehlers-Danlos, which causes weak membranes), vitamin C deficiency, and invasive procedures (amniocentesis)

**Pathophysiology** - Collagen degradation by matrix metalloproteinases (MMPs), increased by infection/inflammation (cytokines such as IL-1, TNF-α, and prostaglandins), weakens the membranes. - Choriodecidual inflammation and apoptosis lead to membrane weakening and rupture.

**Diagnosis** - History of a gush or continuous leakage of fluid. - Sterile speculum exam: pooling of fluid in the posterior vaginal fornix. - Nitrazine test: amniotic fluid is alkaline (pH 7.1-7.3) and turns paper blue (vaginal pH is 4.5-6). False positives: blood, semen, alkaline antiseptics, BV/trichomoniasis. - Ferning: arborization of dried amniotic fluid on microscopy (false positives: cervical mucus, fingerprints). - Ultrasound: decreased amniotic fluid index (oligohydramnios, AFI <5 cm). - Commercial tests: AmniSure (PAMG-1) and ROM Plus (IGFBP-1/AFP). Indigo carmine dye test (amnioinfusion) is a confirmatory option if the diagnosis is still unclear. - **Avoid digital cervical exams** unless the patient is in labor. They shorten latency and increase infection risk. Use a sterile speculum exam instead. - Also assess for infection, abruption, labor, and fetal well-being (NST, ultrasound for presentation and growth). Obtain GBS and chlamydia/gonorrhea cultures.

**Complications** - Preterm labor/delivery: ~50% deliver within 1 week and most within 2-5 weeks, depending on gestational age. - Chorioamnionitis (intraamniotic infection): maternal fever, uterine tenderness, maternal and fetal tachycardia, purulent or foul-smelling fluid, leukocytosis. Treat with broad-spectrum antibiotics (ampicillin + gentamicin) and delivery. - Placental abruption (3-5%). - Umbilical cord prolapse or compression (oligohydramnios, malpresentation). - Neonatal complications: respiratory distress syndrome, IVH, NEC, sepsis. - Pulmonary hypoplasia, limb contractures, and Potter-like facies (fetal deformation sequence) if PPROM occurs before ~24 wk with prolonged oligohydramnios.

**Management (high-yield by gestational age)** - **Any gestational age with labor, chorioamnionitis, abruption, nonreassuring fetal status, or fetal demise:** deliver. - **<24 weeks (previable):** counsel on risks and options (expectant management vs. induction). Prognosis is poor. - **24 0/7-33 6/7 weeks:** expectant management in the hospital with: - Antenatal corticosteroids (betamethasone) to accelerate fetal lung maturity. - Latency antibiotics: ampicillin + erythromycin IV for 48 h, followed by amoxicillin + erythromycin PO to complete 7 days. They prolong latency and reduce infection. - Magnesium sulfate for fetal neuroprotection (reduces cerebral palsy) if delivery is anticipated before 32 weeks. - GBS prophylaxis if labor starts and the GBS status is unknown or positive. Also give tocolysis only for a short course to allow steroids to work (not if infection or abruption is present). - **34 0/7-36 6/7 weeks:** delivery is generally recommended (ACOG). Steroids at this gestational age are individualized. - Avoid amoxicillin-clavulanate (increases NEC risk in neonates).

**Key associations and pearls** - Chorioamnionitis is the major maternal risk, and oligohydramnios is the major fetal risk. - Do NOT perform digital cervical exams, and avoid tocolytics if infection or abruption is present. - Do not confuse PPROM (<37 wk, before labor) with PROM at term (≥37 wk, before labor) or preterm labor with intact membranes. - Fetal lung maturity: corticosteroids (betamethasone) increase surfactant production by type II pneumocytes. - Rh-negative mothers should still receive RhoGAM at the standard indications.